What changed:
-------------

- Support more IPPROTO_TCP socket options: TCP_FASTOPEN, TCP_KEEPIDLE,
  TCP_KEEPCNT, TCP_KEEPINTVL, TCP_QUICKACK, TCP_USER_TIMEOUT.


Bug Fixes:
----------

- Fix IPPROTO_TCP option handling, especially in terms of TCP_MAXSEG.

- Fix a buffer overrun in Cygwin-internal string comparison.
  Fixes: https://cygwin.com/pipermail/cygwin/2020-June/245226.html

- Fix microcode registry lookup for /proc/cpuinfo output.
  Fixes: https://cygwin.com/pipermail/cygwin/2020-May/245063.html
